Fix a number of tests to work correctly with 32/64-wide targets.

Still to be reviewed/fixed: tests/test-*, tests/[cfrs]*

tests/min-float.ispc

@@ -5,7 +5,7 @@ export uniform int width() { return programCount; }
 
 export void f_f(uniform float RET[], uniform float aFOO[]) {
     float a = aFOO[programIndex];
-    RET[programIndex] = min(a, 20.f);
+    RET[programIndex] = min(a, 200.f);
 }
 
 export void result(uniform float RET[]) { RET[programIndex] = 1+programIndex; }